Detent means for push button switch



May 21, 1957 P. HUTT DETENT MEANS FOR PUSH BUTTON SWITCH Filed Oct. 3,1955 QQUQVOV mm W f/mxrfor United States Patent 2,793,257 DETENT MEANSFOR PUSH BUTTON swrrcn Philip Hutt, Milford, Conn., assignor to GeneralElectric Company, a corporation of New York Application October 3, 1955,Serial No. 538,031

3 Claims. (Cl. 200--5) The present invention relates to a multiple pushbutton switch of the type which includes a plurality of push buttons foractuating sliders to effect the closing of one or more pre-selectedelectric circuits when one of the buttons is depressed while preventingthe simultaneous operation of a second push button through a suitable interlocking mechanism.

This invention is an improvement in the push button switch of the basicAndrews Patent No. 2,431,904 which is assigned to the same assignee asis the present invention, and it is a lower cost substitute for thedetent means of the Applicants copending application, Serial No. 404,-627, which was filed on January 18, 1954, and likewise assigned to thesame assignee as is the present invention. This application issued onNovember 8, 1955 as Patent No. 2,7233 17.

The push button switch of the Andrews patent has been widely used formany years for controlling the heating elements of electric ranges. Inrecent years, however, such push button switches have been adapted forthe'control of other types ofelectrical equipment such as room airconditioners which involve motor driven ap paratus. In suchapplications, it is frequently necessary that control switches bearranged so that the controlled circuits cannot be inadvertently openedand immediately reclosed. A situation of this kind may, for instance, beinvolved where a controlled motor isused to drive apparatus so arrangedthat the motor, when its supply circuit is opened, stops under load andcannot be restarted without undesired operation of circuit protectivemeans unless the load is first disconnected from the motor.

An example of such an application is found in the control ofrefrigerating compressors as used in air conditioning equipment whichmay involve a plurality of electric circuits to be controlled. Amultiple push button switch of the general type of the switch describedin the above-mentioned Andrews Patent No. 2,431,904 is well adapted forsuch use to select various operating conditions of the equipment. Whenthe air conditioner is used merely for movement of air (into or out of aroom), one or more fans are operated. If it is desired to cool the room,then a compressor for the refrigerant must be connected in the operatingsystem. It is an inherent characteristic in some of the room airconditioners now on the market that once the motor for driving thecompressor is stopped, it cannot be restarted immediately until anappreciable time has elapsed, in the order of one or two minutes. Duringthis lapse of time, the pressure of the refrigerant on both sides of thecompressor is being equalized by a bleeder system. If an attempt is madeto restart the compressor immediately after it has been stopped, thecompressor motor will stall due to an excessive overload and the circuitprotective fuse or breaker will open. 5

Operating instructions ordinarily furnished with such equipment cautionthe operator against trying to restart the-compressor too soon after ithas been stopped. However, it is desirable that control switchmechanisms for 'ice such equipment-be arranged to prevent thepossibility of inadvertent opening of the compressor motor circuit andits automatic, immediate reclosing.

A difiiculty encountered in attempting to use a switch of the typedescribed in the aforesaid Andrews Patent No. 2,431,904 for the controlof certain room air conditoners is that such a switch permits theinadvertent opening of its circuits followed by an immediate, automaticreclosing. A light pressure on any of the push buttons other than theone previously depressed is transferred by the mechanism into a forcedirected toward opening the electrical circuits. When this pressure isreleased, the circuits would immediately reclose. When initial testswere made with such a switch on a room air conditioner, a casualpressure on the buttons could open the compressor motor circuit and thenpermit it to close again with the result that the motor would be in astalled condition, thereby operating the circuit protective means toopen the circuit. Obviously this condition could not be tolerated.

One solution'of this problem is found in the Applicants copendingapplication, Serial No. 404,627. However, the subject'invention has beenmade in order to accomplish the same results as the invention in saidapplication by using fewer parts and standard switch housings of smallersize so that the switch could be sold at a lower cost.

Accordingly, the principal object of this invention is to provide apositive action in the nature of a snap action for each of the buttonsof a push button switch of the class described by using a simplifieddetent mechanism.

A further object of this invention is to provide a push button switchwith a detent mechanism which may be installed in a standard switchhousing in a location normally occupied by one of the push buttons.

A further object of this invention is to provide a push button switchwith a detent mechanism that may be positioned in any one of thepositions normally occupied by one of the push buttons.

A further object of this invention is to provide a push button switchwith a plurality of movable sliders each having an opening for receivinga detent mechanism comprising a pair of guided pins which are normallybiased apart.

The present invention as herein described is embodied in a push buttonswitch comprising a hollow housing of insulating material, stationarycontacts secured in the housing, and movable contacts cooperativelyassociated with the stationary contacts. There are a plurality ofparallel spring strips secured at their ends to the housing andsupporting .the movable contacts at their free ends. A plurality ofsliders are arranged longitudinally within the housing in side-by-siderelationship and below the spring strips so that they are seated on thebottom wall of the housing. Each slider is provided with one or more camsurfaces on its upper edge for alternately engaging certain of the saidspring strips to effect the opening and closing of the respectivecontacts in certain operating positions of the sliders. A series ofdiagonal working surfaces are likewise formed in each slider to begenerally in alignment with but distinct from similar working surfacesin the other sliders. A plurality of push buttons project into thehousing and are associated with the diagonal working surfaces of thesliders by verticallyguided pins which are supported transversely on thebottom of each push button. Specifically, the transversely-extendingpins of the push buttons are arranged to cooperate with the diagonalworking surfaces to operate the sliders to selected operating positions.

The specific invention disclosed herein relates to a detent mechanismwhich serves'to retard the sliding movement of the sliders. Thismechanism is installed by providing each of the sliders with a generallysquare-shaped opening having one or both of its longitudinally-extendingedges provided with a detent or convex cam surface. 'A pair ofvertically spaced pins extend through these aligned openings in thesliders and are guided by grooves on opposed wallsrof the housing in amanner similar to the pin guide means for the push buttons. This pair ofdetent pins is normally biased apart by apair of C- on a diagonalworking surface of one or more sliders,

thereby tending to move the sliders longitudinally of the housing. In sodoing, the convex cam surface will be temporarily blocked by one of thedetent pins due to the spring action between the pins until the movingforce is great enough to overcome this spring action so that the detentcam surface may move under the pin to the opposite position. The pair ofdetent pins counterbalance each other so that there is no tendency forthe sliders to be forced downwardly and bind on the bottom wall of thehousing or upwardly and become jammed with the spring strips of themovable contacts. Since the detent pins are supported in grooves whichare similar to those supporting and guiding the push buttons, it isapparent that this detent mechanism may be shifted at will dependingupon the location of the detent openings in the sliders in order toattain a preferred spacing of the buttons. Thus, it is only necessary toadd an additional push button position to the switch base in order totake advantage of the detent mechanism of this invention.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

In the drawing:

Fig. 1 is a top plan view of a push button switch embodying my inventionwith a portion of the cover removed so that some of the switch parts maybe identified.

Fig. 2 is a transverse cross-sectional view taken on the lines 2-2 ofFig. 1.

Fig. 3 is a partial cross-sectional, side elevational view taken on thelines 33 of Fig. 1 showing clearly the detent mechanism of thismechanism.

Fig. 4 is a partially exploded isometric view of a portion of thesliders showing the pair of detent pins and the C-shaped spring membersof strip material for biasing them apart.

Fig. 5 is a diagrammatic view showing the position of the sliders andthe movable and fixed contacts when the left-hand button is depressed.

Fig. 6 is a diagrammatic showing similar to that of Fig. 5 when thebutton that is second from the left end has been depressed.

Referring in detail to the drawing, and in particular to Figs. 1-3, 10represents a hollow switch housing comprising a molded base 11 ofsuitable insulating material and a thin cover plate 12 which is rivetedas at 13 to the base to enclose the switch parts. The base is recessedwith a deep longitudinal central cavity 14 and relatively shallow sidecavities 15 and 16. Fixed contacts 17 are mounted on the side 16 of thebase while spring strips 18 of sheet material which carry the movablecontacts 19 are fastened at their opposite ends at the side 15 of thebase, as is best shown in Fig. 2.

The spring strips 13 carrying the movable contacts 19 are normallybiased into engagement with the fixed contacts 17. The positions of themovable contacts are controlled by a group of four sliders 20-23 (Fig.5) read ing from the side 15 to the side 16 which, as shown in Fig. l,are bunched together in side-by-side relation.

The top edge of each slider is formed with a pattern of cam surfaces 24which are adapted to hold the spring strips 18 and consequently themovable contacts 19 away from the fixed contacts. Looking at Fig. 5, itwill be understood that the left-hand contact 19 is held open by the camsurface of the slider 21 while the right-hand contact is held open byboth sliders 22 and 23. In considering Fig. 6, the left-hand contact isclosed while the righthand contact is held open by both sliders 22 and23.

The present invention is shown embodied in a fourposition switch havingfour push buttons which are molded from suitable insulating material,the lower end of which is bifurcated to straddle the sliders 20-23. Eachslider is provided with a series of openings 31 having diiferentcombinations of diagonal working surfaces 32. There is such an opening31 for each push button 30 and theseopenings are generally in alignmentas may be visualized from the diagrammatic showings of Figs. 5 and 6. Ametal pin 33 extends through the bifurcated end of each push button andthrough the aligned openings 31 in the sliders. Such pins 33 are guidedin vertical grooves 34 on opposite side walls of the cavity 14 in thebase. When the cover 12 is fastened over the base, the push buttons 30extend through close-fitting openings in the cover so that the buttonsare guided for straight-line movement by both the pins 33 and the cover12.

The structure which has been recited above, with particular relation tothe reference numerals, is standard switch construction which has beenpracticed for many years under the teachings of the Andrews Patent No.2,431,904 and as clearly illustrated in the applicants before-mentionedcopending application, Serial No. 404,627. This basic switch structurehas proved to be unsatisfactory for use in motor controlling circuitssince a slight pressure on the OFF button would momentarily open thecircuit and if the pressure were quickly released before the button werefully depressed, the tendency would be for. the circuit to again closeto its original position, thereby resulting in the stalling of the motorand the opening of the circuit protective fuse. The present inventionwas made to eliminate this difiiculty by providing the switch with asimulated snap action so that as the movable contacts begin to open orclose when a button is depressed, the force built up to provide thisresult will be initially retarded by a detent mechanism embodying myinvenrtion. After this detent mechanism has been overcome, it issuddenly taken out of action so that the force exerted against thebutton will carry the button to its extreme depressed position.

As seen in Fig. 4, my detent mechanism comprises a pair of detent pins37 which extend through a square vshaped opening 38 in each of thesliders and are biased apart by the G-shaped spring members 39 of stripmaterial which have hook ends so that they do not become disengaged fromthe pins, as is best seen in Fig. 3. The detent openings 38 through thesliders are shown in Fig. 5 as being the second opening from the leftand they occupy about the same space as do the openings 31 which includethe diagonal working surfaces 32. The detent pins 37 are guided ingrooves 40 on opposite walls of the housing which are similar to thegrooves 34 that support the push button pins 33 for straight-linemovement. The lower edge of the detent opening 38 has a convex camsurface 41 so that when the slider moves, the lower detent pin 37 mustride over the convex cam 41 which compresses the springs 39 and retardsthe movement of the sliders. If the position of the switch in Fig. 5 istaken as the datum plane where the left-hand button is depressed and theswitch contacts are open, the operation of the switch will be understoodwhen comparison is made with Fig. 6 showing the condition of the partswhen the second button from the left is depressed. In Fig. 6, thesliders 20, 22, and 23 have not moved from their position as shown inFig. 5. Only slider 21 has shifted to the right since the ,pin 33 of thebutton second from the left has operated on the diagonal working surface42 and shifted the entire slider to the right. As it moves, the convexcam 41 compresses the springs 33% until the lower detent pin 37 hasreached the top of the cam 41. At this point the detent mechanism hasvery little function although after it moves into its extreme positionthe pins stand ready to operate as a detent mechanism when the slidermoves in the opposite direction. Attention is directed to the fact thatin Fig. the diagonal working surface 43 of slider 21 will force the pin33 and hence the left-hand button vertically upward so that it finishesin the position as shown in Fig. 6.

It will be readily appreciated by those skilled in this art that while Ihave chosen to illustrate my invention by showing a detent openinghaving a convex cam surface on the bottom edge of the opening, analternate arrangement would be to have a similar convex cam surfacealong the top edge of the opening so that both detent pins move as thesliders are shifted into the various positions. it is likewiseconceivable that other elements could be substituted for the pair ofdetent pins 37 and the C-shaped springs while retaining the basicprinciple of a springbiased force acting in a direction transversely ofthe plane of movement of the sliders to be in engagement with a convexcam surface on the sliders which would tend to snub or retard themovement of the sliders so that the push buttons will have, in effect, asnap action. My invention has been accomplished by merely increasing thesize of the switch base by one button position since the detentmechanism may be mounted in the same grooves which serve to support thestraight-line movement of the buttons. Thus, there is afforded apossibility to select the placement of the buttons where the detentmechanism may be shifted to any of the button positions depending uponthe location of the detent openings.

Modifications of this invention will occur to those skilled in this artand it is to be understood, therefore, that this invention is notlimited to the particular embodiments disclosed but that it is intendedto cover all modifications which are within the true spirit and scope ofthis invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A multiple push button switch comprising a hollow housing, contactmeans including fixed contacts and movable contacts that are operated bya plurality of sliders, a series of diagonal working surfaces formed oneach of the sliders, and means for actuating the sliders comprising aplurality of push buttons projecting into the housing and guided forstraight-line movement, each button having pin means for engagement withselected ones of the aligned working surfaces as the button is depressedso as to move said sliders to predetermined contact controllingpositions, and detent means for retarding the movement of the sliderscomprising a cutout portion having a convex cam surface in each of thesliders and likewise arranged in alignment with similar cam surfaces onthe remaining sliders, and a spring-biased detent pin extending throughthe sliders and guided for reciprocating movement by fixed wall membersof the switch housing to be in engagement with the said convex camswhereby the force of the spring of the detent pin must be overcomebefore the sliders may shift as a button is being depressed.

2. A multiple push button switch comprising a hollow housing, contactmeans arranged in the housing including fixed contacts and movablecontacts that are controlled by a plurality of longitudinally movablesliders that are arranged in side-by-side relationship, each sliderhaving a series of diagonal working surfaces generally in alignmentwith, although distinct from, such working surfaces in the othersliders, and means for actuating the sliders comprising a plurality ofpush buttons projecting into the housing, each button carrying atransverse pin which is guided in grooves on the opposite side walls ofthe housing and extends through the sliders to operate on the saiddiagonal working surfaces so as to move the sliders to predeterminedcontact controlling positions, and detent means for retarding themovement of the sliders comprising an aligned opening in each sliderwith a convex cam surface extending along at least one of the lengthwiseedges and a pair of vertically spaced pins extending through saidopenings and being supported in opposed grooves in the side walls of thehousing, spring means located between the said pair of pins to bias themapart with at least one pin being in engagement with the said convex camsurfaces whereby the convex cam surfaces force the pins together tocompress the springs before the sliders may shift to a differentposition as a button is being depressed.

3. In a push button switch comprising a hollow housing, contact meansincluding stationary contacts secured in said housing, movable contactscooperatively associated with the stationary contacts, and a pluralityof spring strips secured to the housing and supporting the movablecontacts, a plurality of sliders disposed within the housing and seatedtherein, each slider being provided with one or more cam surfaces foralternately engaging certain of the said spring strips to effect theopening and closing of the respective contacts in certain operatingpositions of the sliders, each slider having a plurality of apertureswith diagonal working surfaces, means for actuating the slidersincluding a plurality of push buttons projecting into the housing andeach having a guided pin projecting through an aperture of each sliderand positioned to engage certain of said working surfaces to operate thesliders to selected operating positions; the invention comprising detentmeans to increase the initial resistance' to the inward movement of eachof the said push buttons so as to provide them with a simulated snapaction including a square-shaped opening in each slider with a convexcam surface extending along at least one lengthwise edge thereof, and apair of pins extending through said openings in the sliders and beingsupported in grooves in opposite walls of the housing, and a C- shapedspring on opposite sides of the sliders with ends that are engageablewith the said pair of pins to bias them apart with at least one pinbeing in engagement with the said convex cam surfaces whereby the forceof the springs must be overcome before the sliders may shift to adifferent position as a button is being depressed.

Kimball Jan. 7, 1941 Andrews Dec. 2, 1947

